Hand grenades are small explosive, incendiary, or smoke producing devices thrown by military or law enforcement personnel in the course of military or law enforcement operations. Hand grenades typically have a body that contains an explosive or chemical filler and a fuze that ignites or detonates the filler in the grenade. The fuze contains a powder train that provides a time delay between the arming of the grenade by a soldier or policeman and the actual detonation of the grenade. The fuze is lit by the action of a spring loaded striker mechanism impacting a primer which ignites a delay element that burns for a predetermined time and then detonates the filler. The grenade is prevented from being armed by a safety handle that blocks the striker mechanism from impacting the primer from a primer. A safety pin locks the safety handle to prevent the arming of the grenade. When the safety pin is withdrawn, the safety lever is free to release from the body of the grenade. When the safety lever is released, the striker spring unwinds and the striker rotates on axis to impact the primer, which then creates a flash of heat that ignites one end of the delay element. The delay element burns down to an igniter at the other end of delay element, which then sets off the main charge or filler of the grenade.
The M201A1 hand grenade fuze had been in use since World War II, mainly in smoke grenades and the like. Variations of the M201A1 fuze are also used in smoke pots, less than lethal grenades and some lethal grenades. The M201A1 fuze is a pyrotechnic delay igniting fuze. The fuze is equipped with a steel safety pin and pull ring. To arm the grenade, the safety pin is removed while holding the lever tight to the grenade body. When the lever is released, a spring-loaded striker rotates and impacts a primer. The impact with the primer ignites a delay element, which initiates the igniter. The igniter then activates a smoke mix in the grenade achieving the desired signal and/or screening effect.